#set_pixel:
#	#a0=x, a1=y
#	addi t0, zero, LEDS #t0 : led adress
#	addi t1, a0, 0   #t1 : counter of x led index
#	addi t2, zero, 0 #t2 : LED word
#	addi t3, zero, 1 #t3 : pixel
#	addi t4, zero, 0 #t4 : counter of x led words
#	addi t5, zero, 0 #t5 : counter of x pos in word
#	addi t7, zero, 8 #t7 : 8, x shift of byte

#get_pixel_address:	
#	addi t5, t1, 0
#	addi t1, t1, -4
#	addi t4, t4, 4
#	bge t1, zero, get_pixel_address
#
#	addi t4, t4, -4
#	add  t0, t0, t4
#	ldw  t2, 0 (t0)
#
#	slli t7, t5, 3
#	add t7, t7, a1
#	sll t3, t3, t7
#	or t2, t2, t3
#
#	stw t2, 0 (t0)
#	ret